The present invention relates to an air-suspension system for a vehicle and a method for the operation of said air-suspension system.
Vehicle air-suspension systems as well as methods for their operation are known, for example, from DE 100 55 108 A1.
An air-suspension system for a vehicle is typically provided with a plurality of air-suspension bellows in the region of the respective wheel suspension of the individual wheels of the vehicle. The air-suspension bellows can be filled with compressed air via a compressed-air delivery device such as a compressor. During practical operation of such an air-suspension system, the level changes at the individual wheel suspensions of the vehicle and thus the processes of filling of the air-suspension bellows must be completed as rapidly as possible. For this reason, it is advisable to design the compressed-air delivery device with sufficient delivery capacity to meet the maximum delivery demand that can develop. Maximum delivery demand will occur if all air-suspension bellows present in the vehicle—usually four in the case of a passenger car—must be filled simultaneously and relatively rapidly with a specified quantity of compressed air.
On the other hand, if only a subset of the air-suspension bellows—two, for example—will be filled with compressed air, for example, to compensate for a leaning condition of the vehicle chassis, it may occur that the delivery capacity of the compressed-air delivery device is overdimensioned for such a situation. This can lead to an undesired large pressure rise on the pressure-outlet side of the compressed-air delivery device, since the compressed-air quantity discharged by the compressed-air delivery device cannot flow rapidly enough into the air-suspension bellows. In an electrically driven compressed-air delivery device, such an undesired large pressure rise can lead to an acoustically perceptible drop in operating rpm. In addition, the electrical current drawn by the compressed-air delivery device's motor can increase to an undesirably high level, in turn causing a safety circuit to trip in the vehicle, among other effects. Finally, an excessive pressure can also lead to damage or increased wear of parts of the compressed-air system.
Accordingly, it is desired to provide, for operation of an air-suspension system for a vehicle, a method in which an undesirably large pressure rise on the pressure-outlet side of the compressed-air delivery device can be avoided with the simplest possible means and with the least possible additional expense.